Power supply unit for feeding a gas-discharge lamp

摘要

A known circuit for feeding a metal-halide lamp for an LCD television projector contains a switching transistor for a switched-mode power supply and four further transistors in a bridge circuit for feeding the lamp. There are particular requirements, in a power supply unit of this type, regarding the height of the power factor which indicates the fraction of the harmonics drawn from the network. According to the most recent regulations, this factor may not overshoot specific values. The object consists in designing a power supply unit of this type in such a manner that the outlay in terms of circuitry regarding transistors and the fraction of the harmonic currents in the network are reduced. The power supply unit contains a switched-mode power supply to whose output the series circuit of two capacitors (6, 7) and the series circuit of two switching transistors (12, 13) are connected. The lamp (8) is connected to the centres (c, d) of the two series circuits. In particular for feeding a metal-halide gas-discharge lamp for an LCD television projection device. <IMAGE>